You’re standing in the grass outside Cerulean City. Your palms are sweaty. If you walk one pixel too far, you ruin the whole thing. Most people remember Pokémon Yellow as the game where Pikachu follows you around and refuses to evolve, but for those of us obsessed with the technical glitches of 1998, it was a playground of broken code. Pokemon yellow gameboy cheats weren't just about using a GameShark or a Pro Action Replay; they were about exploiting the literal memory of the cartridge to do things Nintendo never intended.
Honesty time: the "Mew is under the truck" rumor was a lie. We all wasted hours trying to move that stupid pixelated vehicle near the S.S. Anne. But the actual Mew glitch? That's real. It works because the game's engine is held together by digital duct tape and hope.
The Mew Glitch is the Only Cheat You Really Need
Most kids in the 90s thought Mew was a myth or a giveaway at a mall event you couldn't get to. Turns out, he’s just sitting there in the code, waiting for you to confuse the game’s "Long-Range Trainer" detection. This isn't a cheat code you type in; it’s a sequence of events that tricks the Gameboy into thinking a wild encounter is a specific index number.
First, you need a Pokémon that knows Fly or Teleport. You find a trainer who spots you the moment they appear on screen—specifically the Jr. Trainer on Route 24 or the Gambler on Route 8. You press Start exactly as you walk into their line of sight. If you do it right, the menu pops up before they can challenge you. You Fly away. The game thinks you’re in a battle, but you’re actually at a Pokémon Center.
When you eventually walk onto Route 24 later, your menu will spontaneously open. Close it. Boom. A level 7 Mew appears. It feels like magic. It’s actually just the game reading the Special stat of the last Pokémon you fought and translating that into an encounter ID.
Why MissingNo is Riskier in Yellow Than Red or Blue
We’ve all heard of MissingNo. In Pokémon Red and Blue, he’s a rite of passage. You swim along the coast of Cinnabar Island and suddenly you have 128 Master Balls. In Pokémon Yellow, however, Game Freak tried to fix the "Old Man" glitch. They mostly succeeded, which makes hunting for pokemon yellow gameboy cheats involving the glitch Pokémon a lot more dangerous.
If you force a MissingNo encounter in Yellow, you aren't just getting free items. You're risking a "save file corruption" screen that can wipe your childhood progress in a heartbeat. Yellow uses a different sprite encoding system. When the game tries to render the corrupted "block" sprite of MissingNo, it often crashes the hardware. If you really want to duplicate items in Yellow, you're better off using the M' (00) glitch, but even then, your Hall of Fame data is going to look like a digital fever dream afterward.
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The Mystery of the Safari Zone Walk Through Walls
Remember the frustration of running out of steps in the Safari Zone? You’re three steps away from a Chansey and ding-dong, your time is up.
There is a way to bypass this, but it’s finicky. It involves the "Poison Step" method. Basically, you get your lead Pokémon poisoned and walk until it’s about to faint. You time your entry into a doorway so that the "faint" message triggers exactly as you transition. If the stars align and the lag hits just right, the game forgets you have boundaries. You can walk over trees. You can walk over water. You can walk right out of the map into the "Glitch City" void.
Getting All Three Starters Without Trading
One of the best things about Yellow was that it gave you Bulbasaur, Charmander, and Squirtle for free if you talked to the right NPCs. But maybe you want them at Level 5 right at the start? Or maybe you want a second Pikachu because yours is moody?
This is where the "Trainer Fly" glitch (the same one used for Mew) becomes a Swiss Army Knife. Every trainer in the game has a "Special" stat associated with their Pokémon. By fighting specific trainers and then returning to the "glitch" route, you can force the game to spawn literally any Pokémon in the Pokédex.
- Want a Gengar at level 1? Fight a trainer with a Special stat of 14.
- Want a Nidoking before the first gym? There’s a stat for that too.
It turns the game into a programmable computer. You aren't playing Pokémon anymore; you're playing "Manipulate the RAM."
The Truth About GameShark Codes
If the "natural" glitches are too much work, you probably looked up GameShark codes. Honestly, these were a gamble. A lot of the codes found in old magazines like Tips & Tricks were actually for the Japanese version of the game. If you put a Japanese "Walk Through Walls" code into a US Pokémon Yellow cartridge, you’d often get a black screen or a loud, high-pitched screeching noise.
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The most reliable codes were the ones that modified your inventory directly.0163D9D3 — That’s the classic for Infinite Rare Candies.01017CCF — That’s for the Master Ball.
But here’s the thing: using these takes the soul out of the game. There is something profoundly satisfying about exploiting a glitch that lives in the hardware. Using a GameShark feels like breaking a window to get into a house. Using the Mew Glitch feels like finding a secret door the architect forgot to lock.
Using the Pikachu Off-Screen Glitch
Since Pikachu follows you in this version, the game has to constantly track two sets of coordinates. If you're quick with a ledge jump or a bike transition, you can actually "lose" Pikachu.
If you manage to get Pikachu stuck behind a wall while you move to a new screen, the game's internal pointer for "Follower Object" gets confused. Sometimes this leads to Pikachu turning into a different NPC sprite. I once had a version where Pikachu turned into a Nurse Joy sprite that followed me into the tall grass. It didn't help in battle, but it was hilarious.
Don't Forget the Experience Underflow
This is a weird one. If you have a Pokémon that belongs to the "Medium-Slow" experience group (like Bulbasaur or Mew), and you get it in a battle at Level 1, you can use a specific glitch. If that Pokémon loses a tiny amount of experience points—so small it drops below zero—the game's unsigned integer logic flips out.
Because the game can't comprehend "negative" experience, it assumes you have the maximum possible value. Your Level 1 Pokémon will instantly jump to Level 100 after a single battle. It’s the fastest way to hit the level cap, but it only works with certain growth rates.
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What Most People Get Wrong About Yellow Glitches
People think these cheats "break" the Gameboy. They don't. The Gameboy is a tank. What they do break is the save file's checksum. If you mess with the memory addresses too much, the game will realize the data is "garbage" and delete the save file to protect the cartridge.
Also, a big misconception: you cannot get Celebi in Pokémon Yellow. I don't care what your cousin told you. Celebi didn't exist in the code until Pokémon Gold and Silver. No amount of surfing around Seafoam Islands or talking to the Oaks's aide will make a Gen 2 Pokémon appear in a Gen 1 game.
Making the Most of Your Glitched Playthrough
If you’re going to dive back into pokemon yellow gameboy cheats, do it with a plan. Don’t just spam Rare Candies. Use the Mew glitch to fill your Dex early. Use the Trainer Fly glitch to encounter the version-exclusive Pokémon that aren't supposed to be in Yellow, like Ekans or Koffing.
- Save often. Not just "I caught a Pokémon" saving, but "I'm about to try a glitch" saving.
- Keep a "clean" Pokémon in your PC. If your party gets corrupted, you need a backup to swap in.
- Don't save after encountering MissingNo. Just see him, get your items, and get out.
- Learn the "Special Stat" list. Keep a reference handy of which numbers correspond to which Pokémon.
The beauty of Pokémon Yellow is that it’s a living relic of a time when games were simple enough to be completely understood, yet complex enough to be delightfully broken. Whether you’re trying to finish the Pokédex in an afternoon or just want a level 100 Gengar before you fight Brock, these exploits are your best friend.
Go to Route 24. Find that Jr. Trainer. Press Start. You know what to do.
Practical Next Steps for Your Glitch Hunt
- Check your Pokémon's Special Stat: Before attempting the Mew glitch or any encounter swap, ensure the Pokémon in your party has a Special stat that matches the ID of the Pokémon you want to spawn.
- Verify your version: If you are playing on a Virtual Console (3DS) or an emulator, the Mew glitch still works, but some hardware-specific memory leaks might behave differently than on an original 1998 Gameboy Color.
- Map your route: Identify the "Long-Range Trainers" early so you don't accidentally defeat them. Once they are beaten, you lose the "trigger" for many of the best glitches in the game.